Apparatus for screwing headless threaded fasteners

ABSTRACT

A tool for screwing headless threaded fasteners comprises a receiver having a threaded hole for threadingly receiving an inner end of the fastener, an eccentric element rotatable on the receiver to exert a force against the inner end of the fastener in a manner jamming together the threads of the fastener and hole to resist relative rotation between the fastener and receiver, and a handle for manually applying rotation to the eccentric element. Once the fastener is jammed within the hole, the receiver can be rotated, thus rotating the fastener. The eccentric element may be arranged to directly contact the fastener. Alternatively, a shiftable element may be interposed therebetween to transmit force from the eccentric element to the fastener. The receiver may be provided with a plurality of holes to accommodate differently sized fasteners.

United States Patent [191 Flaig [451 July 1,1975

[ APPARATUS FOR SCREWING HEADLESS THREADED FASTENERS Christian Flaig, Muhlstrasse 1, Aldingen, Germany 221 Filed: Oct. 31. 1973 211 Appl. No.: 411,305

[76] Inventor:

Primary Examiner-Al Lawrence Smith Assistant Examiner-James G. Smith Attorney, Agent, or Firm-Burns, Doane, Swecker & Mathis [5 7] ABSTRACT A tool for screwing headless threaded fasteners comprises a receiver having a threaded hole for threadingly receiving an inner end of the fastener, an eccentric element rotatable on the receiver to exert a force against the inner end of the fastener in a manner jamming together the threads of the fastener and hole to resist relative rotation between the fastener and receiver, and a handle for manually applying rotation to the eccentric element. Once the fastener is jammed within the hole, the receiver can be rotated, thus r0- tating the fastener. The eccentric element may be arranged to directly contact the fastener. Alternatively, a shiftable element may be interposed therebetween to transmit force from the eccentric element to the fastener. The receiver may be provided with a plurality of holes to accommodate differently sized fasteners,

11 Claims, 8 Drawing Figures FTRTENTEU JUL 1 I975 SHEET APPARATUS FOR SCREWING HEADLESS THREADED FASTENERS BACKGROUND AND OBJECTS OF THE INVENTION The invention relates to a screwing tool. The screwing tool according to the invention is suitable for inward and outward screwing of threaded pins, i.e., headless fasteners such as staybolts, tap bolts etc. Hitherto it had been customary and necessary to grasp such fastener bolts either in an area of the shaft free of a thread with a gripping tool or pliers and twist it for the purpose of screwing it in or out. Whenever no shaft area free of thread was available, two nuts would be screwed onto one end of the thread to lock them against each other and then turn this arrangement with the help of a wrench placed on one of the nuts.

Such a procedure is very cumbersome and time consuming, and therefore the invention is based on the general object of obviating or minimizing these problems.

Another object is to create a screwing tool with the help of which it will be possible to screw headless screws in and out without damage to the free threaded end and without additional auxiliary means.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS OF THE INVENTION This task is solved accordint to a preferred embodiment of the invention by a receiver head, provided with at least one threaded hole for the free threaded end of a staybolt, headless screw etc. A tensioning eccentric is pivotally connected to the receiver head in an extension of the axis of the threaded hole, with its pivotal axis extending transversely to the hole; The tensioning eccentric includes eccentric means arranged to apply axial force to a threaded fastener which is threadingly received in the hole. In this fashion, the fastener is locked against rotation in the hole.

The eccentric means may be arranged to directly contact the fastener to apply this axial force. Alternatively, a shiftable element, such as a thust bolt disposed in the hole, may be arranged to be shifted by the eccentric means against the fastener. A hand lever is firmly connected with the tightening eccentric to rotate the latter.

The tool thus is screwed onto the free end of the threaded fastener, i.e. into the threaded hole which is adapted to the thread of this fastener. By then swivelling the hand lever, together with which the tightening eccentric is likewise swivelled, the receiver head is tightened against the screwed-in end of the threaded fastener so that now, during screwing of the tool around the axis of the tightened fastener, the latter is now positively and untwistably connected with the screwing tool.

It is advantageous to provide that the shortest distance of the eccentric surface from its swivelling axis is diametrically opposite to the contact point of the hand lever on the tightening eccentric. In this manner, after screwing-on of the receiver head to the end of the fastener, the possibility exists of swivelling the hand lever in two different directions for the purpose of tightening the eccentric against the fastener. Therefore, the tool can be used in tight places. At the same time, the distance of the eccentric surface from its swivelling axis will increase uniformly in both peripheral directions from the point of shortest distance, i.e. at the same pitch, in order to achieve equal conditions in both swivelling directions during tightening at the same swivelling angle.

Whenever ribs with a V-shaped cross-section extend peripherally along the eccentric surface, said ribs will be tightly pressed into the frontsurface of the fastener and thus form an additional safeguard against twisting, beside the tightening of the threads head on.

Preferably the receiver head has several variable threaded holes distributed over its periphery and is superimposed on a cylindrical base. The receiver head includes a cylindrical bore running perpendicularly to the axis of the threaded holes, and is thereby mounted on the base for relative frictional rotation and against relative axial movement. In such a case it is desirable that the axis of the base extend parallel to and at a distance from the axis of the eccentric. By using a multiholed receiving head, only a single tool needs to be available for various sizes of fasteners, and it will only be necessary during screwing-on of the receiver head onto the end of the fastener to swivel the proper threaded hole into the position in which the surface of the tensionin g eccentric is at the shortest distance from the swivelling axis of the tightening eccentric. Moreover, if the cylinder bore is disposed eccentrically in the receiver head, so that the ratio of depth of the threaded hole to the diameter of the threaded hole of all threaded holes on the periphery is about even, then the receiver head will have the smallest possible diameter and thus also the lowest possible weight.

It will be effective, in order to facilitate the screwingon of the receiver head on one end of the fastener, to make the receiver head frictionally rotatable on the cylinder base. For this purpose an extension, with a larger diameter, can be disposed on one end of the cylinder base. Into this extension the hand lever is inserted, while a spring plate, attached to engage one surface of the receiving head, biases another surface of the receiving head against an edge of the extension.

In case of a screwing tool which is intended for only a single size fastener and which is thus lighter and cheaper, the receiver head can have a forked end with a transverse bore receiving a swivelling bolt of the tightening eccentric. This forked end is disposed opposite the only threaded hole. A thrust bolt, with a head supported by the edge of the of the threaded hole facing the tightening eccentric and with a V-shaped crossed slit, can be provided. This bolt is disposed with its front surface set in the threaded hole for the purpose of transferring power between the tightening eccentric and an end of the fastener.

It is advantageous to provide a knob on the handle at the hind end thereof. The knob can be shaped as a cube with various dodecagonal recesses for nuts for any additional screwing tasks that become necessary. Such nuts can be screwed onto the screwed-in threaded screw, such as a stay bolt.

THE DRAWING The invention will now be explained in detail on the basis of the drawing and in connection with two embodiments by way of example, whereby its advantages, characteristics and properties will be clearly discernible.

FIG. 1 shows one preferred form of screwing tool according to the invention in side view, with the hand lever shown shortened;

FIG. 2 shows a partially broken open side view of the cylinder base with the tightening eccentric;

FIG. 3 shows a sectional cut following line III-III in FIG. 2;

FIG. 4 shows a cross-sectional view of the receiver head of the screwing tool from FIG. 1;

FIG. 5 shows the knob of the handle, developed as a wrench with several dodecagonal openings;

FIG. 6 shows in longitudinal section, a second simplified preferred embodiment of the screwing tool according to the invention with the handle lever shown shortened; 1

FIG. 7 shows the screwing tool from FIG. 6 in the screwed-in position; and

FIG. 8 shows a.view of the front surface of the pressure bolt with V-shaped crossing grooves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First of all, the general picture on the basis of FIG. 1 of the entire screwing tool 10 according to a first embodiment will be described. A receiver head 11, which is shown again in cut through its middle plane in FIG. 4, has three threaded holes 12, 12 12 of various thread sizes. These holes are displaced by 120 in relation to each other. The receiver head has, extending perpendicularly to the plane passing through the center lines of the threaded holes, a cylindrical bore 13. The axis of this bore is somewhat offset from the center of the peripheryof the receiver head. This eccentric arrangement of the cylinder bore 13 relative to the receiving head brings'about the fact that the ratio of the depth of the threaded hole to the threaded hole diameter of all threaded holes is about equal. Preferably, the material of the receiver head is depth-hardened steel.

The cylinder bore 13 of the receiver head 11 receives a cylinder base 14, which is drawn in detail in FIG. 2. The cylinder base 14 has at one end an extension 15 with a largendiameter than the bore. This extension is developed as a hexagonal head through which a transverse opening 16 passes. A hand lever 17 is inserted in this transverse opening. As will be explained later in detail; a hand lever enables the tensioning eccentric to be maneuvered to lock the tool to a fastener after the latteris screwed into the receiving head. The handle lever 17 is offset advantageously in such a way that its end lies approximately in the joint plane of the axis of the threaded holes 12 to 12 with the handle knob 18 lying in the hand. The handle knob 18, which is shown in detail in FIG. 5, has the shape of a cube, whereby one surface of the cube has a bore 19 for inserting the end of the hand lever, while dodecagonal holes 20 20 with different wrench widths are worked into the other surfaces of the cube. I

The receiver head 11 is seated with sliding or frictional fit on the cylinder base 14. In this regard, the axial length of the cylinder base 14 is essentially equal to the length of the cylinder bore 13 of the receiver head. The receiving head is fixed grippingly rotatably on the cylinder base with the help of a spring plate 22, held by a screw'21. The clamping, however, is so light that the receiver head can easily be turned by hand, in order to be able to turn the required threaded hole into a certain position. FIG. 2 shows that a threaded bore 23 is worked into the front surface of the threaded base 14 which is opposite the extension 15, into which threaded bore the screw 21 is screwed firmly.

The cylinder base 14, as can be recognized from FIGS. 2 and 3, is discontinued in its surface by an eccentric section, which represents a tensioning eccentric 24. This tensioning eccentric 24 is at a level which, in case of the receiver head being pushed on to the cylinder base 14, lies adjacent the area of the threaded bores 12 to 12 The displacement of the tensioning eccentric in relation to the axis of the cylinder base 14 has been chosen in the direction of the bore 16. for the hand lever. In other words, a point on the eccentric representing the shortest distance from the axis of the base 14 to the surface of the eccentric, is located diagonally opposite the place of connection of the handle 17 to the base 14 when viewed from above. In the present case the displacement is of such a magnitude that a generatrix of the tensioning eccentric will just be tangent (touch) on the generatrix of the cylinder base.

The generatrix of the tension eccentric has circular ribs 25, which in cross-section are V-shaped. These ribs, when the eccentric is turned, squeeze into the lenticular end of the fastener to press the threads of the fastener against the threads of the threaded hole to produce a tightened state therebetween to still further prevent rotation of the fastener relative to the threaded hole.

The step by step course in the use of the screwing tool is as follows: i

If a staybolt, for example, is to be screwed-in, then the threaded hole 12 to 12 which corresponds to the size of thread of the staybolt, is advanced to a position opposite the hand levers by manually twisting the receiver head. The staybolt can then easily be screwed by hand into the threaded hole, until the inner end thereof abutts against the surface of the tensioning eccentric 24 which lies farthest back in relation to the generatrix of the cylinder base. If now the receiver head with the screwedin or inserted staybolt is twisted relative to the eccentric by holding the staybolt and on swivelling the hand lever 17, then the tensioning eccentric 24 exerts a force on the end surface of the staybolt and begins to jam the thread of the staybolt in the threaded hole of the receiver head. The ribs 25 simultaneously are forced into the len'ticular front surface of the staybolt. After a certain swivelling movement of the hand lever 17, the staybolt is locked absolutely untwistably in the receiver head 11. It can then be screwed in and tightened into a hole provided for it by turning of the entire tool. That is, the handle 17, the base 14, the receiving head 11, and the staybolt can be rotated in unison about the longitudinal axis of the staybolt to install the staybolt into a structure. In order to remove the tool it will be sufficient to swivel the hand lever again into the diametrically opposite position relative to the receiving head, as a result of which the tightening of the staybolt threads in the threaded hole is nullified. The screwing tool can then easily be unscrewed from the staybolt which is now tightly installed.

The releasing and unscrewing of analready tightly installed staybolt or of any headless threaded screw takes place in the reverse order. A detailed description is not needed here. The tightening of the staybolt in the threaded hole of. the receiver head however, is so strong that every tightened staybolt can assuredly be loosened, unless the fastener thread is strippedon its shaft.

As a result of the symmetrical arrangement of surface of the eccentric means of the tensioning eccentric 24 relative to the hand lever 17 when viewed from above it is irrelevant in what direction the hand lever is swivelled during fastener locking. Therefore, in handling of the tool, a swivelling path of no more than about 180 needs to be available, if the hand lever 17, together with the tensioning eccentric, is rotated in reverse direction after every rotation of 180 of the eccentric.

The development of the handle knob 18 with dodecagonal recesses increases the versatility of the screwing tool. It is advantageous if the cube 18 is hollow, so that nuts additionally screwed onto a staybolt can be also be seized thereby, and that the staybolt itself projects through the cube.

A second, simplified preferred embodiment of the invention shown in FIGS. 6 to 8, has a receiver head 22A, which is screwed onto staybolt 21A. The receiver head 22a includes a cylindrical body with a concentric threaded bore 23A threadingly receiving the staybolt. The receiver head 22A is provided with prongs of a fork 24 at its end opposite the threaded hole 23A. A transverse bore penetrates these prongs of the fork, in which a bore swivelling bolt 25A is inserted. This bolt 25A penetrates one end of a swivellable hand lever 26. The head 26' of the swivelling lever 26 defines a tensioning eccentric symmetrically configured relative to the longitudinal axis of the hand lever 26. Thus, the point on the surface of the eccentric 28, which is least distant from the swivelling axis, lies on the longitudinal axis of the hand lever 26. In this case too, therefore, the

distance of the surface of the eccentric from its swivelbolt. In this frontal surface, V-shaped grooves 29 are disposed, in the form of a cross. Such grooves are easily pressed against the front end of the staybolt during tightening of the thrust bolt against'the end of the staybolt through the urging of the tensioning eccentric 26'. The grooves thus also contribute to the further twistproof tightening.

FIG. 7 shows the operating position of this simpler tool during screwing on and off of the end of the staybolt, whereby the threads of the staybolt and hole 23A can be screwed into one another completely free of tension. By swivelling the hand lever 26 in the plane of the drawing to positions according to either FIG. 6 or swivelled by 180 in relation to FIG. 6 the tensioning needed for the immovable holding of the end of the staybolt in the receiver head for the screwing in and out of said staybolt to a machine element etc., will then be achieved.

If desired, the inserted thrust bolt 27 can also be left out in the case of a corresponding shortening of the receiver head 22A, and the staybolt can be screwed-in close to the tensioning eccentric. In addition, the surface of the tensioning eccentric can then be equipped with V-shaped grooves, running in a peripheral direction, as shown and described in connection with the first embodiment. Also the hand lever can have a knob at its free end, into which hexagonal or dodecagonal holes are worked in for variable nuts.

MAJOR ADVANTAGES AND SCOPE OF THE l INVENTION i The preferred tools of the present invention enable a headless screw to be conveniently inserted and/or removed from a structure with minimal effort and minimal chance of damage occurring to the screw. The tool of FIG. 1 enables a single tool to be' adapted for various sized screws. By providing the knob 18 with dodecagonal holes, the same tool can be used to insert or remove nuts on or from the screws.

Although the invention has been described in connection with a preferred embodiment thereof, it will be apreciated by those skilled in the art that additions, modification, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt or studbolt, the tool comprising:

a receiver head having at least one threaded hole for threadingly receiving the inner free end of the threaded fastener;

a tensioning eccentric pivotally connected to said reerting a force on the inner free end of the threaded fastener, when such fastener is thread:

ingly inserted in said threaded hole, to lock the fastener against rotation relative to saidhole; and

a hand lever connected to said tensioning eccentric to rotate said eccentric means.

2. A screwing tool according to claim 1 wherein the I point of the shortest distance of the surface of the eccentric means from its pivotal axis is opposeddiametrically to the place of engagement of the hand lever on the tensioning eccentric.

3. A screwing tool according to claim 2 wherein the distance of the surface of the eccentric means from the pivotal axis increases uniformly in both peripheral directions from the said point of shortest distance.

4. A screwing tool according to claim 1 including ribs of V-shaped cross-section extending along the peripheral surface of said eccentric means.

5. A screwing tool according to claim 1 wherein said receiver head includes a plurality of threaded holes distributed around the periphery of said receiver head; a cylinder base extending through a receiver bore in said receiver head, and said receiver bore extending perpendicularly relative to the axis of said threaded holes; said tensioning eccentric comprising a part of said cylinder base with the axis of said cylinder base extending parallel to and offset from the axis of said eccentric means; said receiving head being mounted on said cyl- 7 inder base for frictional rotation relative th'ereto against axial movement relative-thereto.

6. A screwing toolaccording-to' claim wherein said receiver bore is eccentricallydisposed relative to said receiver head such that the ratio of threaded hole depth to threaded holediameter ,is essentially the same for each of said threaded holes.

7. A screwing tool according to claim 5 wherein said cylinder base includes an extension at one end thereof receiving said hand lever;.said extension being larger than said receiver bore; a springplate being attached adjacent the other end of said cylinder base to bias the receiver head into frictional engagement with said extension.

8. A screwing tool according to claim 1 including a cube elementmounted on the distal end of said hand lever; said cube including sockets for receiving nuts.

9. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt or studbolt, the tool comprising: a receiver head having at least one threaded hole for threadingly receiving the inner free end of the threaded fastener; a tensioning eccentric pivotally connected to said receiver head; the pivotal axis of said tensioning eccentric being arranged transversely to the axis of the threaded hole; said tensioning eccentric including eccentric surface means arranged to be brought into axial alignment with said threaded hole upon rotation of said tensioning eccentric for exerting an axial force on the inner free end of a threaded fastener, when such fastener is threadingly inserted in said threaded hole, to lock the fastener against rotation relative to said hole; a rotatable hand lever connected to said tensioning eccentric to rotate said eccentric surface means; the point of the shortest distance of said eccentric surface means from said pivotal axis being opposed diametrically to the place of engagement of the hand lever on said tensioning eccentric; the distance of said eccentric surface means from said pivotal axis increasing uniformly in both peripheral directions from said point of shortest distance, so that said hand lever may be rotated ineither direction about said pivotal axis to lock said fastener against rotation relative to said hole; said eccentric surface means being arranged to directly contact the said inner free end of an inserted threaded fastener to lock the fastener against rotation; said eccentric surface means including ribs of V-shaped cross section extending along the peripheral surface thereof; said receiver head including a plurality of threaded holes distributed around the periphery of and said receiver head; a'cylinder base'extending through a receiver bore in said receiver head; said receiver bore extending perpendicularly relative to the axis of said threaded holes; said tensioning eccentric comprising a part of said cylinder base with the axis of said cylinder base extending parallel to and offset from the axis of said tensioning eccentric; said receiver head being mounted on said cylinder base for frictional rotation relative'thereto and against axial movement relative thereto; said receiver bore being eccentrically disposed relative to said receiver head such that the ratio of threaded hole depth to threaded hole diameter is essentially the same for each of said'threaded holes; said cylinder base including an extension at one end thereof receiving said hand lever; said extension being larger than said receiver bore; and a spring plate being attached adjacent the other end of said cylinder base to bias the receiver head into frictional engagement with said extension.

10. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt. or studbolt, the tool comprising:

a receiver head having a plurality of threaded holes;

of varying size, such that one of said holes is dimensioned for threadingly receiving the inner free end of the threaded fastener;

a tensioning eccentric pivotally connected'to said receiver head;

said receiver head being rotatable such that said one hole can be broughtinto suitable position for receiving said threaded fastener, with the axis of said one hole being arranged transversely to, v and in intersecting relationship with, the -.pivotal ';,axis of said tensioning eccentric; a 1

said tensioning eccentric including eccentric.-

means arranged to be brought into axialal-ignment with said one threaded hole uponrotation. of said tensioning eccentric for exerting an axialu force on the inner free end of a threadedfas-.

tener, when such fastener is threadingly inserted in said one threaded hole, to lockthe fastener.

against rotation relative to said one hole; and a hand lever connected to said tensioning ec'centric to rotate said eccentric means.

11. A tool according to claim 10 wherein the axis point on said .pivota l said threaded holes intersect at a 

1. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt or studbolt, the tool comprising: a receiver head having at least one threaded hole for threadingly receiving the inner free end of the threaded fastener; a tensioning eccentric pivotally connected to said receiver head; the pivotal axis of said tensioning eccentric being arranged transversely to the axis of the threaded hole; said tensioning eccentric including eccentric means arranged to be brought into axial alignment with said threaded hole upon rotation of said tensioning eccentric for directly contacting the inneR free end of a threaded fastener and exerting a force on the inner free end of the threaded fastener, when such fastener is threadingly inserted in said threaded hole, to lock the fastener against rotation relative to said hole; and a hand lever connected to said tensioning eccentric to rotate said eccentric means.
 2. A screwing tool according to claim 1 wherein the point of the shortest distance of the surface of the eccentric means from its pivotal axis is opposed diametrically to the place of engagement of the hand lever on the tensioning eccentric.
 3. A screwing tool according to claim 2 wherein the distance of the surface of the eccentric means from the pivotal axis increases uniformly in both peripheral directions from the said point of shortest distance.
 4. A screwing tool according to claim 1 including ribs of V-shaped cross-section extending along the peripheral surface of said eccentric means.
 5. A screwing tool according to claim 1 wherein said receiver head includes a plurality of threaded holes distributed around the periphery of said receiver head; a cylinder base extending through a receiver bore in said receiver head, and said receiver bore extending perpendicularly relative to the axis of said threaded holes; said tensioning eccentric comprising a part of said cylinder base with the axis of said cylinder base extending parallel to and offset from the axis of said eccentric means; said receiving head being mounted on said cylinder base for frictional rotation relative thereto and against axial movement relative thereto.
 6. A screwing tool according to claim 5 wherein said receiver bore is eccentrically disposed relative to said receiver head such that the ratio of threaded hole depth to threaded hole diameter is essentially the same for each of said threaded holes.
 7. A screwing tool according to claim 5 wherein said cylinder base includes an extension at one end thereof receiving said hand lever; said extension being larger than said receiver bore; a spring plate being attached adjacent the other end of said cylinder base to bias the receiver head into frictional engagement with said extension.
 8. A screwing tool according to claim 1 including a cube element mounted on the distal end of said hand lever; said cube including sockets for receiving nuts.
 9. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt or studbolt, the tool comprising: a receiver head having at least one threaded hole for threadingly receiving the inner free end of the threaded fastener; a tensioning eccentric pivotally connected to said receiver head; the pivotal axis of said tensioning eccentric being arranged transversely to the axis of the threaded hole; said tensioning eccentric including eccentric surface means arranged to be brought into axial alignment with said threaded hole upon rotation of said tensioning eccentric for exerting an axial force on the inner free end of a threaded fastener, when such fastener is threadingly inserted in said threaded hole, to lock the fastener against rotation relative to said hole; a rotatable hand lever connected to said tensioning eccentric to rotate said eccentric surface means; the point of the shortest distance of said eccentric surface means from said pivotal axis being opposed diametrically to the place of engagement of the hand lever on said tensioning eccentric; the distance of said eccentric surface means from said pivotal axis increasing uniformly in both peripheral directions from said point of shortest distance, so that said hand lever may be rotated in either direction about said pivotal axis to lock said fastener against rotation relative to said hole; said eccentric surface means being arranged to directly contact the said inner free end of an inserted threaded fastener to lock the fastener against rotation; said eccentric surface means including ribs of V-shaped cross-section extending along the peripheral surface thereof; said receiver head including a plurality of threaded holes distributed around the periphery of said receiver head; a cylinder base extending through a receiver bore in said receiver head; said receiver bore extending perpendicularly relative to the axis of said threaded holes; said tensioning eccentric comprising a part of said cylinder base with the axis of said cylinder base extending parallel to and offset from the axis of said tensioning eccentric; said receiver head being mounted on said cylinder base for frictional rotation relative thereto and against axial movement relative thereto; said receiver bore being eccentrically disposed relative to said receiver head such that the ratio of threaded hole depth to threaded hole diameter is essentially the same for each of said threaded holes; said cylinder base including an extension at one end thereof receiving said hand lever; said extension being larger than said receiver bore; and a spring plate being attached adjacent the other end of said cylinder base to bias the receiver head into frictional engagement with said extension.
 10. A screwing tool suitable for screwing a headless threaded fastener such as a staybolt or studbolt, the tool comprising: a receiver head having a plurality of threaded holes of varying size, such that one of said holes is dimensioned for threadingly receiving the inner free end of the threaded fastener; a tensioning eccentric pivotally connected to said receiver head; said receiver head being rotatable such that said one hole can be brought into suitable position for receiving said threaded fastener, with the axis of said one hole being arranged transversely to, and in intersecting relationship with, the pivotal axis of said tensioning eccentric; said tensioning eccentric including eccentric means arranged to be brought into axial alignment with said one threaded hole upon rotation of said tensioning eccentric for exerting an axial force on the inner free end of a threaded fastener, when such fastener is threadingly inserted in said one threaded hole, to lock the fastener against rotation relative to said one hole; and a hand lever connected to said tensioning eccentric to rotate said eccentric means.
 11. A tool according to claim 10 wherein the axis of said threaded holes intersect at a point on said pivotal axis. 